Algal Bloom - high concentrations of phytoplankton (algae) that
occur when conditions, such as light and nutrients, are sufficient to
support rapid growth.
Anoxic - a condition where no oxygen is present.
Anthropogenic - of human origin.
Benthic Organisms - organisms living in or on bottom sediments in
Biomass - the quantity of living matter,
expressed as a concentration of weight per unit area in aquatic systems.
Chlorophyll - the green pigments in plant cells, such as
phytoplankton, that are active in photosynthetic reactions; chlorophyll
concentration is often used as a measure of phytoplankton biomass.
Deep Trough Region - the deepest portion of the Chesapeake Bay
mainstem which is located from the Annapolis Bay Bridge to just below the
confluence of the Potomac River. This area experiences severe oxygen
depletion of bottom waters during summer.
Detritus - particulate organic matter that is freshly dead or
Ecosystem - an interactive system which includes the organisms of a
natural community together with their physical and chemical environment.
Estuary - semi-enclosed, tidal, coastal body of saline water with a
free connection to the sea and within which sea water is measurably diluted
with fresh water derived from land drainage; commonly the lower end of a
Euphotic Zone - the surface layer of a body of water which receives
sufficient sunlight to support photosynthesis by phytoplankton or rooted
Eutrophication - a complex response by aquatic systems to the excess
input of nutrients that stimulate phytoplankton growth. The increased
phytoplankton growth leads to other problems such as low dissolved oxygen
and shading of submerged aquatic vegetation.
Food Web - the network of pathways within an ecosystem that link
organisms to their prey and to their predators.
Hypoxic - a condition where only very low levels of oxygen are
Inorganic Compounds - chemical compounds generally not containing
carbon and thus not classified as organic compounds; in aquatic systems,
inorganic forms of nutrients such as nitrogen and phosphorus are most
readily utilized by growing phytoplankton.
Metabolism - the chemical and physical processes occurring in living
Microgram (μg) - a unit of mass equal to one millionth of a gram.
Milligram (mg) - a unit of mass equal to one thousandth of a gram.
Nutrients - chemicals, primarily nitrogen and phosphorus, that are
required for growth, development and reproduction of plants.
Organic Compounds - chemical compounds containing the element
carbon; these compounds are the primary constituents of living matter.
Photosynthesis - the synthesis of organic compounds from water and
carbon dioxide using light energy in the presence of chlorophyll.
Phytoplankton - microscopic plants (algae) suspended in the water
Phytoplankton Productivity - the rate at which a phytoplankton
community is growing, often expressed as the generation of biomass in terms
of carbon; also known as primary productivity.
Plankton - aquatic organisms, either plants or animals, that are
found drifting passively or swimming weakly in the water column.
Pycnocline - the region in a water column where water density
changes rapidly, usually due to changes in salinity and temperature; in the
Chesapeake Bay, the pycnocline region separates fresher, surface waters
with a net flow down-Bay from saltier, bottom water with a net flow up-Bay.
Recycling - as applied to aquatic nutrients, these are the cyclical
pathways traveled by elements that result in chemical changes between
organic and inorganic forms; these changes are often mediated by biological
Sediment Oxygen Demand (SOD) - the rate at which biological and
chemical reactions taking place in bottom sediments consume oxygen from the
overlying water column.
Turbidity - decreased clarity of water caused by the presence of
dissolved or suspended matter.
Water Column - term used to refer to a water body in its vertical
Zooplankton - small, often microscopic, animals suspended in the
2. Understanding The Bay's Problems
3. Program Description
4. Chemical and Physical Properties
6. Benthic Organisms
7. Ecosystem Processes
8. Pollutant Inputs
9. Management Strategies and the Role